Gates, whose Bill & Melinda Gates Foundation gives a reported $4 billion a year to fight malaria, said making the cause a priority was "a joke."

He said: "I certainly love the IT thing, but when we want to improve lives, you've got to deal with more basic things like child survival, child nutrition."

"Take this malaria vaccine, [this] weird thing that I'm thinking of. Hmm, which is more important, connectivity or malaria vaccine? If you think connectivity is the key thing, that's great. I don't."

Saving the world, one Facebook link at a time

Earlier this year, Zuckerberg asked whether connectivity was a "human right" and launched a "rough plan" to accelerate the rate at which those in the developing world are obtaining online access.

The plan involves using white spectrum data, compressing data, making apps that consume less data and offering free "zero-rating" data with smartphone plans in the developing world.

"I think that connecting the world will be one of the most important things we all do in our lifetimes, and I'm thankful every day to have the opportunity to work with all of you to make this a reality," said Zuckerberg in his proposal.

"When you're dying of malaria, I suppose you'll look up and see that balloon, and I'm not sure how it'll help you. When a kid gets diarrhoea, no, there's no website that relieves that," he said in August.